Modeling transient churn-annular flows in a long vertical tube

Alves, M. V. C., Waltrich, P. J., Gessner, T. R., Falcone, G. and Barbosa, J. R. (2017) Modeling transient churn-annular flows in a long vertical tube. International Journal of Multiphase Flow, 89, pp. 399-412. (doi: 10.1016/j.ijmultiphaseflow.2016.12.001)

Full text not currently available from Enlighten.

Abstract

This work investigates the transient behavior of high gas fraction gas-liquid flows in vertical pipes (annular and churn flows). Hyperbolic balance equations for mass, momentum and entropy are written for the gas and liquid, which is split between a continuous film and droplets entrained in the gas core. Closure relationships to calculate the wall and interfacial friction and the rates of droplet entrainment and deposition were obtained from the literature. A finite-difference solution algorithm based on a coefficient matrix splitting method was implemented to deal with sharp variations in the spatial and temporal domains, such as pressure and phase holdup waves. The model results were compared with steady-state experimental data from eight different sources, totaling more than 1500 data points for pressure gradient, liquid film flow rate and void/core fraction. The absolute average deviation between the model and the data was 17% for the pressure gradient and 5.8% for the void fraction. A comparison of the model results with fully transient air-water data generated in a 49-mm ID, 42-m long vertical pipe is also presented. The experimental results consist of two outlet pressure-induced and two inlet mass flow rate-induced transient tests. Two main transient parameters are compared, namely the local void fraction and the pressure difference between selected points along the test section and the outlet (taken as a reference). The comparisons between the experiments and the numerical model indicate that the model was capable of describing the transient annular to churn flow transition with absolute average deviations of 14.5% and 7.9% for the pressure difference and void fraction, respectively.

Item Type:Articles
Additional Information:The authors thank the sponsors of the JIP on Liquid Loading in the Operation of Gas Fields: Mechanisms, Prediction and Reservoir Response, coordinated by Texas A and M University, of which the Federal University of Santa Catarina (UFSC) and TU Clausthal were participating universities. Marcus Alves thanks the CNPq for the PhD scholarship at UFSC (Grant No. 142781/2008-8), and for the one-year internship scholarship at Texas A and M University (Grant No. 201817/2010-1). We also thank CENAPAD/Unicamp, for providing access to their supercomputing facility where the computer program was run.
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Falcone, Professor Gioia
Authors: Alves, M. V. C., Waltrich, P. J., Gessner, T. R., Falcone, G., and Barbosa, J. R.
College/School:College of Science and Engineering > School of Engineering > Systems Power and Energy
Journal Name:International Journal of Multiphase Flow
Publisher:Elsevier
ISSN:0301-9322
ISSN (Online):1879-3533
Published Online:02 December 2016

University Staff: Request a correction | Enlighten Editors: Update this record